Prognostic implications of myocardial contractile reserve in patients withcoronary artery disease and left ventricular dysfunction

OBJECTIVES This study was performed to assess the prognostic implications o f myocardial contractile reserve (MCR) in patients with coronary artery dis ease (CAD) and left ventricular (LV) dysfunction. BACKGROUND MCR during dobutamine stress echocardiography (DSE) identifies v iable myocardium that may improve in function after revascularization. Whet her revascularization influences prognosis of patients with MCR has not bee n determined. METHODS We performed DSE in 80 patients with CAD and LV dysfunction (ejecti on fraction less than or equal to 40%). Viable myocardium was defined in dy sfunctional myocardial segments as enhanced thickening and contraction duri ng low-dose dobutamine (5 to 10 mcg/kg/min). Serial prospective follow-up w as obtained in all patients (mean follow-up 2.2 +/- 1.1 years). RESULTS Among 52 patients treated medically, there were 20 cardiac deaths. By multivariate analysis, the number of dysfunctional segments demonstratin g MCR was the strongest predictor of survival (p < 0.03). Patients with MCR had better initial survival during medical therapy than did those without MCR, but this survival advantage was not maintained beyond three years. In contrast, survival was excellent in patients with MCR who underwent myocard ial revascularization. Among 58 patients with MCR in greater than or equal to 5 myocardial segments, survival at three years was 93 +/- 6% in the 24 p atients who were revascularized but only 49 +/- 15% in the 34 treated medic ally (p < 0.02). CONCLUSIONS Myocardial contractile reserve is a significant predictor of su rvival in patients with CAD and LV dysfunction undergoing medical therapy. Although patients with MCR have an initial survival advantage, this advanta ge is lost over the course of three years. In contrast, survival in patient s with significant MCR is enhanced by revascularization. (J Am Coll Cardiol 1999; 34:730-8) (C) 1999 by the American College of Cardiology.